An Optimal Lifecycle Residential Building Technology Analysis Using Net-Zero Operational Energy and Thermal Comfort

Purpose: The purpose of this research was to evaluate relative IBT performance by implementing a design-oriented approach that ensured net-zero homes for residential units through evaluation of the operational energy consumption, while maintaining good thermal comfort in South Africa. Design/ Methodology/ Approach: Ten innovative building technologies (IBTs) were used for the analysis based on a 60-square-meter floor area housing unit. The secondary data was obtained from weather files, building designs, options for building materials, components, and fixtures. Building energy optimization using the sequential searching algorithm and Monte Carlo methods were applied to obtain the results. Gqeberha (Port Elizabeth) was the study area selected as a basis for the research. Koppen Geiger climatic classification was used. Findings: After calibrating the energy model, the best thermal comfort was obtained for clothing insulation levels of 0.7–1.3. Fired clay, hempcrete and steel stud IBTs had best thermal comfort in Gqeberha (index of 99.5% 99.7% and 100.0% respectively). The order of performance under total operational energy consumption was fired clay, hempcrete and others (10 inch grid—insulated concrete forms), in that order. The steel stud IBT had the highest operational energy consumption. Practical Implications: Operational energy consumption tended to yield better thermal comfort (lower POR index value) and vice versa within the temperate oceanic climate (Cfbx). Since the calibrated energy model showed that South African households spend only 10% of total operational energy, for space conditioning, households have to utilize clothing with high insulation levels (0.8–1.3) in order to achieve the best thermal comfort. Social Implications: The results indicate that when behavioural patterns are taken into consideration and occupants are allowed to flexibly select different clothing insulation levels throughout the year, all the IBTs supported good thermal comfort (highest hours outside acceptable thermal comfort were four hours annually or 0.05%). Investing in localized hemp farming (for production of hempcrete) and localized clay brick production within Gqeberha would produce lower energy intensive building materials that support good thermal comfort and minimize lifecycle energy use. Originality and Value: The paper adds value to previous research by uniquely placing emphasis on evaluation of relative IBT performance based on net zero operational energy design and thermal comfort, using Gqeberha (Port Elizabeth) as the study area.